Pneumatic action for pianos.



W. G. BETZ.

PNEUMATIC ACTION FOR,P|ANOS. APPLICATION FILED MAY8.19I4.`

l 1 97,5 9 6 I. Patented Sept. 12, 1916.

WILLIAM G. BETZ, OF BUFFALO, NEW YORK.

PNEUMATIC ACTION EGR PIANS.

Specification of Letters Patent.

Patented Sept. 12, 1916.

Application led May 8, 1914. Serial No. 837,130.

specification.

My invention relates to pneumatic actions for pianos, the principalfeatures looking` more particularly to a simplified valve constructionand the method of supporting the action levers controlled thereby.Referring more particularly to the valve mechanism, I have found thatwith my construction a very effective control of the hammer action issecured and one in which a smaller air duct or vent in the tracker barmay be used and Still secure a very .good operation. Also I have so hungthe action levers that said levers and their supporting arms may beindependently removed. A

I will now refer to the accompanymg drawing for a better understandingof my invention in which like reference characters indicate like partsand in which- .Figure 1 is a sectional view illustrating the controlmechanism of one key; Fig. 2 is a face view of one valve mechanism withthe cover of the air chamber removed; Fig.

3 is a side elevation of a valve lever; Fig.

lis a left side view of Fig. 3; Fig. 5 is a detail view of a combinedvalve lever sup-.

port and valve seat, andFig. 6 is a sectional view through the center ofFig.

In the preferred embodiment of my in` vention as illustrated, I providea so-called air chest or chamber A, comprising verti` cally disposedfacing walls 1. and 2 having spacers as 3, 4, the cap or wall 2 beingattached by screws 5 so that it may be readily removed. This chamber Ais, of course, of such a lengt-h and width as to suitably take care ofthe desired number of valve mechanisms, as will be readily understood.

A single valve mechanism B is shown comprising a plate G having acentrally disposed air port '7 formed so as to provide -a valve seat S,and above said port a pair of inwardly projecting ears 9 are formed,having concave /formations 10 for supporting the valvelever shaft. Plate6 is secured to the inner surface of the wall 1 preferably by screws 11,the valve seat 8 projecting yinto a chamber 12 having a valve seat 13,said chamber 12 having an atmosphere duct 14 and bellows duct 15.

A valve lever 27 is provided, having a pointed shaft 25, which is sprungbetween the resilient armsl) and held between the concaved portions 10in such a manner that the depending lever 27 is free to reciprocatewithout any lateral movement, thus doing away with guides, such as havebeen previously used. vAt the free end of lever 27, a valve 29 isadjustably attached b v means of a screw 30, said valve having facingspreferably of leather, which act upon valve seats S and 13.

At a point preferably intermediate of the pivoted end of lever 27 andthe valvesupport 30, a buffer 31 is adjustably secured, said buffercoperating with a dia-` phragm 32, which is preferably of rubber orleather, and suitably fastened over the diaphragm actuating chamber 23.Chain` ber 33 is preferably round, and a duct 3l leads therefrom to atube extending to its tracker bar port 3G. 'A connecting duct 37 leadsfrom the main air chamber A to each duct 34, there being a cap 3Sprovided with a small opening inserted inieach duct 37 to allow only asmall flow of air. A tube from chamber A is also connected to theAvacuum pump to create a vacuum in chamber A in a well known manner.

It will, of course, be understood that in using my invention, the airchest is made wider than shown, and the associated bellows and valvemechanisms are staggered in accordance with well known practice.

An action-operating bellows C is suitably fastencd to the wall 1 inconnection with duct 15 and is connected to a hammer action lever 16`bymeans of a connecting rod- 17, which is pivotally attached at its upperend and held to the bellows extension 18 by a pair of ball faced nuts19. Each action lever 1G is pivotally secured to an arm 20, which isdetachably secured to a rack or bar 2l by means of screws 22, said rackbeing suitably supported, preferablv by screws 23. Anoverhanging'portion Ztl of arm 20 carries an adjustable stop 2l,

whereby the upward travel offaction lever-*105 16 isdetermined. Anadjustable buffer screw 2G is also carried by lever 16 which acts-uponthe action mechanism D, as will be readily understood.

In the operation of the action, a vacuum 110 is created in the airchamber A .y suitable means, and with the music sheet covering the duct36 a vacuum is also created in duct 34. Thus the atmospheric pressureagainst valve 29 tends to hold valve lever 27 in its normal orinoperative position, and therefore the bellows C is maintained open.Upon opening tracker port 36, duct 311 tends to come up to atmosphericpressure, resulting'in a pressure against diaphragm 32 by the pressurein chamber 33. Buffer 31 therefore acts upon lever 27, which causesvalve 29 to normal or air chamber port seat and engage the latmosphereduct seat 13, whereby the bellows chamber is connected to the chamber Aby ducts 15. `A vacuum is thus createdin the bellows chamber, allowingthe atmospheric pressure to close the bellows, whereby the arm 18 risesand through connecting rod 17 and lever 1G the hammer action mechanism Dis actuated. Upon closure of port 36 again, duct 35 and chamber 33lbeing connected to chamber A again have the pressure therein reduced sothat the atmospheric pressure acting upon valve 29 through duct 14,forces the valve 29 against its seat 8 and thus the bellows chamberbeing connected to atmosphere through ducts 15, 14, again opens andrestores the action mechanism D.

What I claim as new and desire to secure by Letters Patent is:

l. A pneumatic action for pianos comprising an air chamber, a valveplate secured to an inner vertical wall thereof, 4and having Lan airport and valve seat, a pair of inwardly projecting resilient arms forsaid plate disposed above the port and having facing concave portions, avalve lever having'a pointed-end shaft'supported by said concaveportions whereby said lever depends opposite said port, and a valve forsaid port supported by said lever.

2. A pneumatic action-for pianos comprising an air chamber, a valveplate secured to an inner wall thereof, a pair of inwardly projectingarms for said plate having facing concave portions, a valve lever havinga pointed supporting shaft lcarried by said concave portions, said valveplate having an air duct and a valve seat on the outer side thereof, anda valve for said seat having a valve stem projecting through said portand carried by said lever.

3. A pneumatic action for pianos comprising an air chamber having facinginner walls, a valve lever disposed within said chamber and pivotallysupported at one end in said chamber, an air port through one of saidwalls opposite the free end of the lever, al valve carried at the freeend of the lever for controlling said port, a plate secured to one ofsaid walls for supporting said leverand having a seat for said valve, anaction operating bellows connected with said port, a diaphragm on theopposite wall, an air duct whereby said diaphragm may be oscillated, anda buffer carried by said lever in operative relation with Asaiddiaphragm.

4. A pneumatic action for musical instruments comprising an airehamber,a valve plate secured thereto, a valvel lever, a pointed shaft for saidlever, a coperating valve and port for said lever and platerespectively, and a pair of resilient arms extending from said platehaving facing concave portions for supporting said valve lever by saidpointed shaft and whereby said arms may be readily sprung apart toremove said lever.

Signed by me at Chicago, county of Cook, and State of Illinois, in thepresence of two witnesses.

l wrLLrAM G. BETZ.

Witnesses 'GEORGE E. MUELLER,

VILLIAM H. FEINDT.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

